The present invention relates generally to golf clubs of the iron type, and more particularly to novel golf club irons of the perimeter weighted type which provide substantially improved distance, accuracy and consistency over prior golf irons.
Recent advances in golf club iron design have introduced the concept of peripheral or perimeter weighting the club head wherein a significant portion of the weight of the head is distributed in a predetermined pattern about the perimeter of the club head. The perimeter weighting extends generally peripherally of a cavity in the back of the club head, and also peripherally of the "sweet spot" on the ball-striking face of the club head. Ideally, the sweet spot, which is determined by the center of mass of the club head, alternatively termed the center of gravity, is located generally centrally on the ball-striking face of the club head. Conventionally, the ball-striking face is defined by a planar surface having a predetermined loft angle and a plurality of parallel spaced grooves or score lines formed therein which are disposed generally horizontally when the club head is in its normal ball addressing orientation. During play, striking a golf ball off-center from the sweet spot can adversely affect the distance, trajectory, direction and spin imparted to the ball, thus affecting the consistency of results between shots with a particular loft iron. Further, and a problem particularly encountered by golfers of lower skill level, the club head may rotate about an axis generally parallel to the axis of the club shaft at the moment of impact with a ball due either to under or over rotation of the golfer's hands, or due to off-center striking of the ball. Such rotation of the club head further reduces the accuracy, distance, trajectory and consistency desired, frequently resulting in slicing or hooking of the ball.
Perimeter weighted golf irons of the aforedescribed type, which may also be termed "cavity back" irons, are believed to provide a larger sweet spot area on the striking face of the iron, thereby allowing a ball to be struck at a point spaced or off-center from the exact point on the club face aligned with the center of mass of the iron, termed the exact sweet spot, with fewer adverse consequences than experienced with non-cavity irons. Known perimeter weighted golf irons generally create a plurality of substantially concentric elliptical force lines about the exact sweet spot on the ball-striking face. A ball impacted on a given elliptical force line will have substantially the same impact energy imparted to the ball irrespective of the relationship of the point of impact to the exact sweet spot on face of the iron. For example, different points of impact on a given elliptical force line may be spaced from the sweet spot at different distances but will result in equal impact energy being imparted to the ball.
A significant drawback in known perimeter weighted irons is that the major axis of the concentric elliptical force lines is inclined to the parallel grooves in the ball-striking face of the iron, generally extending from high in the heel portion of the club to low on the toe portion. This is due to the disproportionate amount of mass associated with a club head neck or hosel in relation to the remainder of the club head. As a result, the effective off-center distance or spacing from the exact sweet spot on the club face that a ball may be impacted, and particularly in a horizontal off-center direction, without incurring the aforementioned adverse consequences is significantly reduced over a design where the major axis of the concentric elliptical force lines is parallel to the grooves in the club face.
Accordingly, perimeter weighted golf irons wherein the major axis of the concentric elliptical lines of force is substantially parallel to the grooves in the club face would provide significantly improved performance over known perimeter weighted irons by improving the distance, accuracy and consistency attained with iron shots.